This is my code for Jump Action using the new input system:

/// JUMP action callback    
public void Jump(InputAction.CallbackContext context)
{
   if (context.performed)
   {
      //hold down button: full height JUMP
      rigidBody.linearVelocity = new Vector2(rigidBody.linearVelocity.x, jumpPower);
   }
   else if (context.canceled)
   {
      //light pressure: half height JUMP
      rigidBody.linearVelocity = new Vector2(rigidBody.linearVelocity.x, jumpPower * 0.5f);
   }
}

It works fine, but to avoid the player floating around, I also added a function that allows him to jump only if he is touching the ground. This is the function:

private bool isGrounded()
{
    if (Physics2D.OverlapBox(groundCheckPos.position, groundCheckSize, 0, GroundLayer))
    {
        return true; 
    }
    else
    {
        return false;
    }
}

Hence, I modified the jump function as follows:

/// JUMP action callback    
public void Jump(InputAction.CallbackContext context)
{
    if (isGrounded())
    {
        if (context.performed)
        {
            //hold down button: full height
            rigidBody.linearVelocity = new Vector2(rigidBody.linearVelocity.x, jumpPower);
        }
        else if (context.canceled)
        {
            //light pressure: half height
            rigidBody.linearVelocity = new Vector2(rigidBody.linearVelocity.x, jumpPower * 0.5f);
        }
    }
}

The issue is that now the jump is always FULL height, the light pressure is not working anymore. By debugging the code using some print statements, I observed that by performing the same action (i.e., slow button pressure for half jump) almost always Unity executes the *context.performed *action. Only rarely, it executes the half jump.

I only inserted a condition on a bool variable. I cannot figure out why it is not working correctly any more. Am I missing something?